What should you know about metronidazole dark urine?

Urine may look darker when you have not had enough fluid, especially after vomiting, diarrhoea, heat exposure, or heavy sweating. Metronidazole can also alter urine colour in some people. A medicine-related colour change is not the same as a sign of organ injury, but colour alone cannot tell the difference.

Dark urine with yellowing of the skin or eyes, pale stools, marked nausea, loss of appetite, itching, or pain under the right ribs needs prompt medical advice because these symptoms can point to a liver or bile-flow problem. Dark urine may also occur with an infection or another condition.

Note when the colour started, how dark it is, and whether it changes after drinking fluids. Drink normally unless a clinician has told you to restrict fluids. Take metronidazole exactly as prescribed, and do not stop it or restart it without advice. Avoid alcohol during treatment and for the interval advised by your prescriber after the last dose.

Contact the prescriber or a pharmacist soon, particularly if the colour persists, becomes tea-coloured, or appears with other symptoms. They may review your medicines and arrange urine or blood tests.

Seek urgent medical help for dark urine with yellow eyes or skin, confusion, severe weakness, repeated vomiting, fainting, very little urine, or severe abdominal pain. Get emergency help for trouble breathing, facial swelling, or collapse. These warning signs should not be explained away as a routine medicine effect.

Ask whether the colour could be caused by metronidazole, dehydration, or another medicine; whether you should continue the course; and whether liver or urine tests are needed. Mention every medicine, supplement, recent illness, and any change in bowel symptoms.